<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style>
      * {
        margin: 0;
        padding: 0;
      }
      body {
        height: 100vh;
      }
      .container {
        height: 100%;
        overflow: hidden; /* 创建BFC */
      }
      .left-column {
        height: 100%;
        float: left; /* 左侧列浮动 */
        width: 200px; /* 左侧列固定宽度 */
        background-color: blue;
        color: #fff;
        padding: 10px;
      }
      .right-column {
        height: 100%;
        background-color: #ccc;
        padding: 10px;
        /* overflow: hidden; */
      }
    </style>
  </head>
  <body>
    <div class="container">
      <div class="left-column">
        <!-- 左侧列内容 -->
        side
      </div>
      <div class="right-column">
        <!-- 右侧列内容 -->
        main
      </div>
    </div>
  </body>
</html>
